Because of the increasing popularity of unrestrained access to broadband services by, for example, portable computing devices, there is an increasing need to extend the range of nodes such as access points associated with wireless networks, including but not limited to wireless local area networks (WLANs) and wireless metropolitan area networks (WMANs) described and specified in the 802.11, 802.16 and 802.20 standards. The effective proliferation of wireless networks depends heavily on sustaining and increasing performance levels as user demands increase.
Performance shortcomings between actual and specified performance levels can be caused by attenuation of the radiation paths of radio frequency (RF) signals, which are typically transmitted at frequencies of 2.4 GHz or 5.8 GHz in an operating environment such as an indoor environment. Base or AP to receiver or client ranges are generally less than the coverage range required in a typical home, and may be as little as 10 to 15 meters. Further, in structures having split floor plans, such as ranch style or two story homes, or those constructed of materials capable of attenuating RF signals, areas in which wireless coverage is needed may be physically separated by distances outside of the range of, for example, an 802.11 protocol based system.
Attenuation problems may be exacerbated in the presence of interference in the operating band, such as interference from other 2.4 GHz devices or wideband interference with in-band energy. Still further, data rates of devices operating using the above standard wireless protocols are dependent on signal strength. As distances in the area of coverage increase, wireless system performance typically decreases. Lastly, the structure of the protocols themselves may affect the operational range.
One common practice in the mobile wireless industry to increase the range of wireless systems is through the use of repeaters. For pure physical layer repeaters, problems and complications can arise in that the random packet nature of typical WLAN protocols provides no defined receive and transmit periods. Because packets from each wireless network node are spontaneously generated and transmitted and are not temporally predictable, undesirable consequences such as packet collisions may occur.
One system, described in U.S. application Ser. No. 10/516,327, which is a PCT national stage application based on international application no. PCT/US03/16208, resolves many localized transmission and reception problems by providing a repeater that isolates receive and transmit channels using a frequency detection and translation method. The WLAN repeater described therein allows two WLAN units to communicate by translating packets associated with one device at a first frequency channel to a second device using a second frequency channel. Since the repeater operates as a physical layer device, the media access control (MAC) address of the packets are not modified, as would be the case in a repeater configured as a layer 2 or higher device. The direction associated with the translation or conversion, such as from the first frequency channel associated with the first device to the second frequency channel associated with the second device, or from the second frequency channel to the first frequency channel, depends upon a real time configuration of the repeater and the WLAN environment.
For example, the WLAN repeater may be configured to monitor both frequency channels for transmissions and, when a transmission is detected, translate the signal received on the first frequency channel to the other frequency channel, where it is transmitted to the destination node. It is important to note that the frequency translating repeater described in the above application acts in near real time to receive, boost and retransmit packets.
While addressing many of the problems in the art, the frequency translating repeater described in U.S. application Ser. No. 10/516,327 lacks certain control message management capabilities such as the ability to modify control message signals to, for example, prevent other transmitters from transmitting additional signals to the repeater while the repeater transmits a modified signal to intended recipients. More specifically, the above repeater cannot prevent the other transmitters from responding to the modified signal during transmission of the modified signal.